London: A mysterious lead coffin found close to the site of king Richard III's grave at the Grey Friars friary has been opened and studied by experts from the University of Leicester.

The coffin was discovered inside a much larger limestone sarcophagus during a second excavation of the site, in August 2013 - one year after the remains of the former king of England were unearthed.

Inside the lead coffin, archaeologists found the skeleton of an elderly woman. The high status female was in one of 10 graves discovered in the grounds of the medieval complex, including that of Richard III, six of which were left undisturbed.

"Although it might seem unusual that Richard III is the only male skeleton found inside the Grey Friars church, the other four skeletons all being female."

"But it must be remembered that we have only excavated five of the 10 identified graves in the church's chancel with the potential for hundreds more burials elsewhere inside the church, the other friary buildings and outside in the cemetery," said Grey Friars site director Mathew Morris, who led the dig.

"Statistically, the sample is too small to draw any conclusions to the significance of so many women at Grey Friars."

"Richard III would certainly not have been the only male buried here during the friary's 300 year history and historic records list at least three other men buried in the church," Morris added.

The lead coffin, with an inlaid crucifix, the location of her burial in presbytery of the friary's church (possibly close to the high altar) meant that she had a special significance to the holy Catholic order.

The discovery is the first example of an intact medieval stone coffin to be unearthed in Leicester during modern excavations.

"This makes it a unique discovery which will provide important new insights into the lives of the people of medieval Leicester," Morris said.